1. Field of the Invention
This invention relates to an image input apparatus, and, more particularly, to an image input apparatus for imaging (e.g. photographing) a document or a picture and which can change its imaging range.
2. Description of the Related Art
Recently, in accordance with the diffusion of image compression/encoding techniques and digital communication networks, recommendations for service provisions, protocol provisions, multimedia multiplexing frame configuration provisions and the like for AV (audio-visual) services, such as TV (or video) conference systems and video telephones, have been established, and various kinds of communication terminals have also been proposed. In particular, camera apparatuses for inputting images of various kinds of objects have attracted notice as a subsystem of a video conference system.
FIG. 5 is a schematic block diagram illustrating the configuration of a conventional camera apparatus. In FIG. 5, a camera 110 is mounted on a panning head 112 capable of performing panning and tilting. A camera/panning head control circuit 114 controls photographing conditions, such as zooming, focusing, exposure and the like, of the camera 110, as well as the rotation of the panning head 112 within the horizontal plane and the vertical plane (i.e., the panning and tilting of the camera 110).
A signal representing an image photographed by the camera 110 is subjected to compression/encoding by an encoding circuit 116, and the obtained signal is transmitted to a communication partner terminal (not shown) via a communication interface (I/F) 118 and a communication network 119.
A control circuit 120 controls the camera/panning head control circuit 114 and the encoding circuit 116 in accordance with user instructions input at the user's own terminal and control commands received from the communication partner terminal. For example, the user of the terminal where the illustrated camera apparatus is installed inputs user instructions (such as zooming, panning, tilting and the like) using a pointing device attached to the terminal (such as a mouse, a keyboard or the like) while displaying the image photographed by the camera apparatus on a monitoring picture surface (e.g. CRT monitor). The control circuit 120 supplies the camera/panning head control circuit 114 with control commands corresponding to the input user instructions. The camera/panning head control circuit 114 controls the camera 110 and the panning head 112 so as to provide a user-terminal instructed state.
Camera/panning head control commands from the communication partner terminal are transferred to the camera/panning head control circuit 114 via the network 119 and the communication interface 118, and the camera/panning head control circuit 114 controls the camera 110 and the panning head 112 so as to provide a communication partner-terminal instructed state (which is instructed by the operator of the communication partner terminal). Camera/panning head control commands from the communication partner terminal are, in some cases, transferred to the camera/panning head control circuit 114 via the communication interface 118 and the control circuit 120. In such a case, functional blocks may be more or less differently recognized.
For such a camera apparatus, it would be advantageous to assign a target region within an object or a photographing field of view, and to photograph the assigned region while magnifying it. Particularly, when giving an explanation to the communication partner while photographing an object with the camera apparatus of the user's own terminal, the target region is frequently changed during the explanation. Accordingly, it is important to provide the camera apparatus with such an operational environment that the target region can be easily and smoothly assigned and changed.
Conventionally, when controlling zooming, panning, tilting and the like of the camera apparatus at the transmission side, the zooming ratio is changed and the panning and tilting angles are set while watching an image displayed on the monitoring picture surface of the user's own terminal. In general, the user explains an object to the communication partner while indicating the region of the object about which the user explains. Thus, the user must sequentially indicate the region of the object being explained and then control the camera to properly image that region. This indicates that the user must frequently move his eyes between the object mounted adjacent the camera apparatus and the monitoring picture surface, thereby causing very troublesome operations.